The present invention relates to vehicle safety apparatus, and in particular to a safety apparatus in which a first signal indicating the presence of driving activity and a second signal indicating the absence of such activity are generated to measure the alertness of a vehicle driver.
In a prior art vehicle safety apparatus, the number of steering oscillations per unit time are counted to measure the degree of alertness of a vehicle driver and if the number of such oscillations falls below a predetermined value, an alarming device will be activated to alert the drawsy driver. Due to the various roadway conditions including the different number of curves in roadway of countryside or of city areas, the frequency of steering oscillations or of movements of an accelerator pedal increases in the city areas, while it decreases in highway cruising. Therefore, it is desirable to compensate for such roadway characteristics in order to produce a valid alarm signal.
The primary object of the present invention is to compensate for various roadway characteristics such as the number of curves in roadway of different localities to generate a valid alarm signal.